Many might think USD's recent breakdown is transitory. But the thing is, the only way to temporarily prop up USD is to hike the FFR, which will sink stocks, which will likely force more QE, which then in turn will sink USD. On the other hand, if not propped up by the tightening of money supply, every USD drop is equivalent of a market rate hike - because you have to charge more interest for debt issued in a sinking currency. Keynesianism is full of such impossibilities conflicting one another, especially at the end of a Keynesian boom.